CN108896785A - The modulation-demodulation circuit and modulation-demo-demodulation method of force-balanced accelerometer - Google Patents
The modulation-demodulation circuit and modulation-demo-demodulation method of force-balanced accelerometer Download PDFInfo
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- CN108896785A CN108896785A CN201810757505.0A CN201810757505A CN108896785A CN 108896785 A CN108896785 A CN 108896785A CN 201810757505 A CN201810757505 A CN 201810757505A CN 108896785 A CN108896785 A CN 108896785A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
- G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
- G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
- G01P15/125—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by capacitive pick-up
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H11/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties
- G01H11/06—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties by electric means
Abstract
The present invention provides the modulation-demodulation circuit and modulation-demo-demodulation method of a kind of force-balanced accelerometer, and circuit includes square wave generative circuit, differential capacitor, signal conditioning circuit and signal demodulating circuit；Square wave generative circuit includes+12V power supply, -12V power supply, the 1st single-pole double-throw switch (SPDT) and crystal oscillator；Signal demodulating circuit includes the 2nd single-pole double-throw switch (SPDT), the 5th resistance (R5), the 2nd capacitor (C2) and the 4th resistance (R4).Advantage is：Circuit structure is simple, only need a crystal oscillator, two single-pole double-throw switch (SPDT)s, 5 resistance, 2 capacitors that whole modulation-demodulation circuits can be completed, for the modulation-demodulation circuit formed compared to conventional bridge oscillating circuit, two-way reverse amplification circuit and multiple MOS field effect transistors, multiple resistance, multiple capacitors,, circuit debugging convenience few using number of elements, and its power consumption is very low.
Description
Technical field
The invention belongs to vibration measurement technique fields, and in particular to a kind of modulation /demodulation electricity of force-balanced accelerometer
Road and modulation-demo-demodulation method.
Background technique
Force-balanced accelerometer is a kind of electric signal for being changed into acceleration physical signal convenient for measurement
Test equipment is to carry out shock and vibration in many fields such as industry, national defence to measure common test equipment.
In force-balanced accelerometer, the application of different capacitance force-balanced accelerometer is more universal, can will be by
The acceleration of survey is converted to the electric capacitance change of capacitor, has many advantages, such as that dynamic response is good, is able to achieve heed contacted measure.
In the prior art, the modulation-demodulation circuit of different capacitance force-balanced accelerometer generally uses following two side
Case is realized：1) bridge oscillator circuit is formed using operational amplifier, triode etc. and generates high_frequency sine wave, then respectively by high frequency
The top crown of sensor differential capacitor is sent into after sine wave reversed one times of driving twice, bottom crown carries out signal modulation.And it is intermediate
The high frequency modulated vibration signal of pole plate output demodulates, output via the demodulator circuit of the elements such as field-effect tube, resistance composition
Represent the low-frequency voltage signal of vibration；2) high_frequency sine wave, the high_frequency sine wave are generated using elements such as digital signal processors
It directly acts in the middle plate of sensor differential capacitor, low frequency signal is directly modulated into high-frequency signal.Then pass through two
Performance parameter consistent charge amplifying circuit in road simultaneously amplifies two capacitors of differential capacitor, the voltage signal of two groups of capacitors output
Low-frequency vibration signal is demodulated to by phase-sensitive demodulating circuits with the digital signal processor output waveform by phase shift processing.
The modulation-demodulation circuit of above two different capacitance force-balanced accelerometer, is primarily present following problems：(1) whole
A modulation-demodulation circuit power consumption is larger, generally 0.24W~0.48W (20mA~40mA@12V)；(2) use number of devices and
Type is more, with structure is complicated and problem at high cost.
Summary of the invention
In view of the defects existing in the prior art, the present invention provides a kind of modulation-demodulation circuit of force-balanced accelerometer
And modulation-demo-demodulation method, it can effectively solve the above problems.
The technical solution adopted by the present invention is as follows：
The present invention provides a kind of modulation-demodulation circuit of force-balanced accelerometer, including square wave generative circuit, differential
Capacitor, signal conditioning circuit and signal demodulating circuit；
Wherein, the square wave generative circuit includes+12V power supply, -12V power supply, the 1st single-pole double-throw switch (SPDT) and crystal oscillation
Device；The differential capacitor includes top crown, middle plate and bottom crown；Wherein, the top crown and the bottom crown are solid
Fixed plate；The middle plate is movable plate, and the middle plate and measurand link, when measurand carries out acceleration
When movement, the middle plate is driven to move along a straight line between the top crown and the bottom crown；The signal demodulation
Circuit includes the 2nd single-pole double-throw switch (SPDT), the 5th resistance (R5), the 2nd capacitor (C2) and the 4th resistance (R4)；
1st single-pole double-throw switch (SPDT) have 1A input terminal, 1B input terminal, 1X output end, 1Y output end and
1C control terminal；The 1A input terminal is connect with+12V the power supply, and the 1B input terminal is connect with -12V the power supply；
The 1X output end is connect with the top crown of the differential capacitor；The bottom crown of the 1Y output end and the differential capacitor
Connection；The 1C control terminal is connect with the output end of the crystal oscillator；
The output end of the middle plate of differential capacitor is connected to one end of the signal conditioning circuit；Pass through signal condition electricity
Road carries out conditioning processing to the high-frequency signal of middle plate output modulated；
2nd single-pole double-throw switch (SPDT) have 2A input terminal, 2B input terminal, 2X output end, 2Y output end and
2C control terminal；The 2A input terminal is connect with the other end of the signal conditioning circuit；The 2B input terminal and the 4th electricity
Hinder one end connection of (R4), the other end ground connection of the 4th resistance (R4)；The 2X output end is connected to the one of the 5th resistance (R5)
End；The other end of 5th resistance (R5) draws two branches, and a branch is connect with signal output end；Another branch is connected to
One end of 2nd capacitor (C2), the other end ground connection of the 2nd capacitor (C2)；2Y output end is empty pin；2C control terminal and crystal
The output end of oscillator connects.
Preferably, the signal conditioning circuit includes concatenated operational amplifier and signal filter unit；The dynode
The output end of plate is connected to the input terminal of the operational amplifier；The output end of the operational amplifier is connected to the signal filter
The input terminal of wave unit；The output end of the signal filter unit is connected to the 2A input terminal of the 2nd single-pole double-throw switch (SPDT).
Preferably, the signal filter unit includes the 1st capacitor (C1), the 1st resistance (R1), the 2nd resistance (R2) and the 3rd electricity
It hinders (R3)；
The input terminal of 1st capacitor (C1) is connect with the output end of the operational amplifier；1st capacitor (C1)
Output end draws two branches, and a branch is connected to one end of the 1st resistance (R1), the other end ground connection of the 1st resistance (R1)；Separately
One branch is connected to one end of the 2nd resistance (R2), and the other end of the 2nd resistance (R2) is connected to one end of the 3rd resistance (R3), the
The other end of 3 resistance (R3) is connected to the 2A input terminal of the 2nd single-pole double-throw switch (SPDT).
The present invention also provides a kind of modulation-demo-demodulation methods of the modulation-demodulation circuit of force-balanced accelerometer, including with
Lower step：
Step 1, crystal oscillator exports the alternate signal of low and high level by certain frequency, and simultaneous transmission gives the 1st respectively
The 1C control terminal of single-pole double-throw switch (SPDT) and the 2C control terminal of the 2nd single-pole double-throw switch (SPDT)；
Step 2, for the 1st single-pole double-throw switch (SPDT), when the crystal oscillator exports high level, 1A input terminal and the
The conducting of 1X output end, 1B input terminal are connected with 1Y output end, when the crystal oscillator exports low level, 1A input
End is connected with 1Y output end, and 1B input terminal is connected with 1X output end；Therefore, when the crystal oscillator presses certain frequency
When exporting the alternate signal of low and high level, 1X output end loads same frequency to top crown, amplitude is respectively+12V and -12V
High-frequency square-wave signal；The high frequency square wave that 1Y output end loads same frequency to bottom crown, amplitude is respectively -12V and+12V
Signal, being loaded top crown and bottom crown respectively, amplitude is identical, high-frequency square-wave signal of opposite in phase；
Step 3, the middle plate of the differential capacitor acted on by acceleration signal has electrical signal of reaction output, the induction telecommunications
Number amplitude and phase it is directly proportional to the size and Orientation of acceleration signal, middle plate of the high-frequency square-wave signal to differential capacitor
Output signal has modulating action；The middle plate of differential capacitor exports the high-frequency signal modulated, which successively leads to
Operational amplifier is crossed to amplify and after signal filter unit is filtered, be transferred to the of the 2nd single-pole double-throw switch (SPDT)
2A input terminal；By signal demodulating circuit synchronous demodulation to low frequency signal, the low frequency signal and acceleration signal are linearly related；
Wherein, signal demodulating circuit synchronous demodulation to low frequency signal process, specially：
When crystal oscillator exports high level, 2A input terminal is connected with 2X output end, 2B input terminal and 2Y
Output end conducting；At this point, the 2nd capacitor (C2) is in charged state, i.e.,：High-frequency signal after signal conditioning circuit improves passes through
After 2nd single-pole double-throw switch (SPDT) and the 5th resistance (R5), charge to the 2nd capacitor (C2)；When crystal oscillator exports low level, the
2A input terminal is connected with 2Y output end, and 2B input terminal is connected with 2X output end；At this point, the 2nd capacitor (C2) is in electric discharge
State, i.e.,：2nd capacitor (C2) discharges to the 5th resistance (R5) and the 4th resistance (R4)；The 2nd capacitor (C2) is in alternately to fill
In electricity and discharge process, since the conducting resistance of the 2nd single-pole double-throw switch (SPDT) is far smaller than the 4th resistance (R4), charging time
Very short, discharge time is very long；Because in the high level period, the 2nd capacitor (C2) quick charge obtains accurate amplitude information；?
Low level period, the 2nd capacitor (C2) slowly discharge, and keep original amplitude information, to extract tune at the 2nd capacitor (C2) end
The envelope amplitude of wave processed, i.e. low frequency signal, to realize demodulating process.
The modulation-demodulation circuit and modulation-demo-demodulation method of force-balanced accelerometer provided by the invention have following
Advantage：
Circuit structure is simple, it is only necessary to which a crystal oscillator, two single-pole double-throw switch (SPDT)s, 5 resistance, 2 capacitors can be completed
Whole modulation-demodulation circuits, compared to conventional bridge oscillating circuit, two-way reverse amplification circuit and multiple MOS field effect transistors, Duo Ge electricity
For the modulation-demodulation circuit that resistance, multiple capacitors form, circuit debugging convenience few using number of elements, and its power consumption is very low.
Detailed description of the invention
Fig. 1 is the circuit diagram of the modulation-demodulation circuit of force-balanced accelerometer provided by the invention；
Fig. 2 is the schematic diagram of single-pole double-throw switch (SPDT) provided by the invention；
Fig. 3 is the waveform diagram for the high-frequency square-wave signal that upward bottom crown provided by the invention applies；
When Fig. 4 is that upper bottom crown does not apply high-frequency square-wave signal, the low frequency signal waveform diagram of middle plate output；
When Fig. 5 is that upper bottom crown applies high-frequency square-wave signal, the waveform for the high-frequency signal of middle plate output modulated
Figure；
Fig. 6 is the waveform diagram of demodulating process.
Specific embodiment
In order to which the technical problems, technical solutions and beneficial effects solved by the present invention is more clearly understood, below in conjunction with
Accompanying drawings and embodiments, the present invention will be described in further detail.It should be appreciated that specific embodiment described herein only to
It explains the present invention, is not intended to limit the present invention.
The present invention provides the modulation-demodulation circuit and modulation-demo-demodulation method of a kind of force-balanced accelerometer, is applied to
The electronic surveying field of low-frequency vibration vibration measurement, main industry to be applied includes seismic monitoring, large scale structure vibration monitoring, water
Modulation-demodulation circuit function in force-balanced accelerometer can be effectively reduced in the vibration monitorings such as library dam, power station, nuclear power station
Consumption.
With reference to Fig. 1, the modulation-demodulation circuit of force-balanced accelerometer includes square wave generative circuit, differential capacitor, letter
Number conditioning circuit and signal demodulating circuit；
Wherein, square wave generative circuit includes+12V power supply, -12V power supply, the 1st single-pole double-throw switch (SPDT) and crystal oscillator；Difference
Dynamic condenser includes top crown, middle plate and bottom crown；Wherein, top crown and bottom crown are fixed polar plate；Middle plate is
Movable plate, middle plate and measurand link, and when measurand carries out acceleration movement, drive middle plate in upper pole
It moves along a straight line between plate and bottom crown；Signal demodulating circuit includes the 2nd single-pole double-throw switch (SPDT), the 5th resistance R5, the 2nd capacitor
C2 and the 4th resistance R4；
1st single-pole double-throw switch (SPDT) has 1A input terminal, 1B input terminal, 1X output end, 1Y output end and 1C
Control terminal；1A input terminal is connect with+12V power supply, and 1B input terminal is connect with -12V power supply；1X output end and differential capacitor
Top crown connection；The connection of the bottom crown of 1Y output end and differential capacitor；The output end of 1C control terminal and crystal oscillator
Connection；Therefore, the 1X output end of the 1st single-pole double-throw switch (SPDT), the output signal of 1Y output end are respectively connected to top crown, lower pole
Plate is, it can be achieved that modulate middle plate output signal.1X, 1Y output end output signal of 1st single-pole double-throw switch (SPDT) are high frequency
Signal, as carrier signal.
The output end of the middle plate of differential capacitor is connected to one end of signal conditioning circuit；By signal conditioning circuit,
Conditioning processing is carried out to the high-frequency signal of middle plate output modulated；
2nd single-pole double-throw switch (SPDT) has 2A input terminal, 2B input terminal, 2X output end, 2Y output end and 2C
Control terminal；The connection of the other end of 2A input terminal and signal conditioning circuit；2B input terminal is connect with one end of the 4th resistance R4,
The other end of 4th resistance R4 is grounded；2X output end is connected to one end of the 5th resistance R5；The other end of 5th resistance R5 draws two
A branch, a branch are connect with signal output end；Another branch is connected to one end of the 2nd capacitor C2, and the 2nd capacitor C2's is another
One end ground connection carries out High frequency filter by the 2nd capacitor C2；2Y output end is empty pin；2C control terminal and crystal oscillator
Output end connection.
Wherein, in Fig. 1, signal conditioning circuit includes concatenated operational amplifier and signal filter unit；Middle plate
Output end be connected to the input terminal of operational amplifier；The output end of operational amplifier is connected to the input of signal filter unit
End；The output end of signal filter unit is connected to the 2A input terminal of the 2nd single-pole double-throw switch (SPDT).
Signal filter unit includes the 1st capacitor C1, the 1st resistance R1, the 2nd resistance R2 and the 3rd resistance R3；
The input terminal of 1st capacitor C1 and the output end of operational amplifier connect；The output end of 1st capacitor C1 draws two branch
Road, a branch are connected to one end of the 1st resistance R1, the other end ground connection of the 1st resistance R1；Another branch is connected to the 2nd electricity
One end of R2 is hindered, the other end of the 2nd resistance R2 is connected to one end of the 3rd resistance R3, and the other end of the 3rd resistance R3 is connected to the 2nd
The 2A input terminal of single-pole double-throw switch (SPDT).
As a kind of specific implementation, two single-pole double-throw switch (SPDT)s can choose model MAX4527, also can choose
MAX4526；The model 32.768Khz of crystal oscillator, or this frequency can be generated by frequency dividing circuit using high-frequency crystal oscillator
Rate signal；The model TLE2061 of operational amplifier, or the super low-power consumptions operation such as TLE2062 or TLE2064 is put
Big device, such as selects TL084 operational amplifier, OP177 operational amplifier, and the power consumption of entire circuit is high.
The present invention also provides a kind of modulation-demo-demodulation methods of the modulation-demodulation circuit of force-balanced accelerometer, including with
Lower step：
Step 1, crystal oscillator exports the alternate signal of low and high level by certain frequency, and simultaneous transmission gives the 1st respectively
The 1C control terminal of single-pole double-throw switch (SPDT) and the 2C control terminal of the 2nd single-pole double-throw switch (SPDT)；
Step 2, for the 1st single-pole double-throw switch (SPDT), when crystal oscillator exports high level, 1A input terminal and 1X are defeated
Outlet conducting, 1B input terminal are connected with 1Y output end, when crystal oscillator exports low level, 1A input terminal and 1Y
Output end conducting, 1B input terminal are connected with 1X output end；Therefore, when crystal oscillator exports low and high level by certain frequency
The high frequency square wave letter that when alternate signal, 1X output end loads same frequency to top crown, amplitude is respectively+12V and -12V
Number；The high-frequency square-wave signal that 1Y output end loads same frequency to bottom crown, amplitude is respectively -12V and+12V, thus makes
Pole plate and bottom crown are loaded that amplitude is identical, high-frequency square-wave signal of opposite in phase respectively；It is single-pole double-throw switch (SPDT) with reference to Fig. 2
Schematic diagram；When upper bottom crown does not apply high-frequency square-wave signal shown in Fig. 3, middle plate output signal is as shown in Figure 4
Low frequency signal, but when upper bottom crown apply high-frequency square-wave signal shown in Fig. 3 when, middle plate output signal is such as Fig. 5 institute
The signal shown.Here it is signal modulation processes.
Step 3, the middle plate of the differential capacitor acted on by acceleration signal has electrical signal of reaction output, the induction telecommunications
Number amplitude and phase it is directly proportional to the size and Orientation of acceleration signal, middle plate of the high-frequency square-wave signal to differential capacitor
Output signal has modulating action；The middle plate of differential capacitor exports the high-frequency signal modulated, which successively leads to
Operational amplifier is crossed to amplify and after signal filter unit is filtered, be transferred to the of the 2nd single-pole double-throw switch (SPDT)
2A input terminal；By signal demodulating circuit synchronous demodulation to low frequency signal, the low frequency signal and acceleration signal are linearly related；This
In invention, by the voltage signal of differential capacitor output after the 2nd single-pole double-throw switch (SPDT), by the end 2X of the 2nd single-pole double-throw switch (SPDT)
Output, high frequency signal is filtered out via the 2nd capacitor C2, and is extracted low-frequency vibration signal by the 2nd both ends capacitor C2.
Wherein, signal demodulating circuit synchronous demodulation to low frequency signal process, specially：
When crystal oscillator exports high level, 2A input terminal is connected with 2X output end, 2B input terminal and 2Y
Output end conducting；At this point, the 2nd capacitor C2 is in charged state, i.e.,：High-frequency signal after signal conditioning circuit improves passes through the
After 2 single-pole double-throw switch (SPDT)s and the 5th resistance R5, charge to the 2nd capacitor C2；When crystal oscillator exports low level, 2A input
End is connected with 2Y output end, and 2A input terminal voluntarily keeps circuit voltage signal itself, does not output signal to the outside；2B is defeated
Enter end to be connected with 2X output end；At this point, the 2nd capacitor C2 is in discharge condition, i.e.,：2nd capacitor C2 is to the 5th resistance R5 and the 4th
Resistance R4 electric discharge；It is in the 2nd capacitor C2 alternately during charging and discharging, charge and discharge process such as Fig. 6, due to the 2nd list
The conducting resistance of double-pole double throw switch is far smaller than the 4th resistance R4, therefore the charging time is very short, and discharge time is very long；Therefore, in height
Level periods, the 2nd capacitor C2 quick charge reach the peak value of output signal with regard to charging in the 2nd capacitor C2 short time, it is accurate to obtain
Amplitude information；In the low level period, the 2nd capacitor C2 slowly discharges (i.e. voltage holding), discharge capacity very little in the short time, almost
The peak value of output signal is maintained, i.e.,：Original amplitude information is almost kept, to extract modulating wave at the 2nd end capacitor C2
Envelope amplitude, i.e. low frequency signal, to realize demodulating process.
The operating current test method of force-balanced accelerometer is as follows, accesses in+the 12V of+12V power supply and sensor
End one ammeter of concatenation equally concatenates an ammeter with the -12V of sensor incoming end in -12V power supply, and dynamic balance accelerates
When spending sensor normal operation, the numerical value of the ammeter in+12V, -12V circuit is recorded respectively, two values are added as
The operating current of the sensor, the total power consumption which can be obtained the sensor multiplied by 12.Through testing, in the present invention, ±
Two kinds of power supply total currents of 12V are 6mA, general power 0.072W.This power is far below similar force-balanced accelerometer
About 20mA electric current, 0.24W general power.
The modulation-demodulation circuit and modulation-demo-demodulation method of force-balanced accelerometer provided by the invention, are especially exchanged
Wave generation circuit and demodulator circuit processed have carried out special designing, to have the following advantages that：
Circuit structure is simple, it is only necessary to which a crystal oscillator, two single-pole double-throw switch (SPDT)s, 5 resistance, 2 capacitors can be completed
Whole modulation-demodulation circuits, compared to conventional bridge oscillating circuit, two-way reverse amplification circuit and multiple MOS field effect transistors, Duo Ge electricity
For the modulation-demodulation circuit that resistance, multiple capacitors form, circuit debugging convenience few using number of elements, and its power consumption is very low.
The above is only a preferred embodiment of the present invention, it is noted that for the ordinary skill people of the art
For member, various improvements and modifications may be made without departing from the principle of the present invention, these improvements and modifications are also answered
Depending on protection scope of the present invention.
Claims (4)
1. a kind of modulation-demodulation circuit of force-balanced accelerometer, which is characterized in that including square wave generative circuit, differential electricity
Appearance, signal conditioning circuit and signal demodulating circuit；
Wherein, the square wave generative circuit includes+12V power supply, -12V power supply, the 1st single-pole double-throw switch (SPDT) and crystal oscillator；Institute
Stating differential capacitor includes top crown, middle plate and bottom crown；Wherein, the top crown and the bottom crown are fixed pole
Plate；The middle plate is movable plate, and the middle plate and measurand link, when measurand carries out acceleration movement
When, drive the middle plate to move along a straight line between the top crown and the bottom crown；The signal demodulating circuit
Including the 2nd single-pole double-throw switch (SPDT), the 5th resistance (R5), the 2nd capacitor (C2) and the 4th resistance (R4)；
1st single-pole double-throw switch (SPDT) has 1A input terminal, 1B input terminal, 1X output end, 1Y output end and 1C
Control terminal；The 1A input terminal is connect with+12V the power supply, and the 1B input terminal is connect with -12V the power supply；It is described
1X output end is connect with the top crown of the differential capacitor；The bottom crown of the 1Y output end and the differential capacitor connects
It connects；The 1C control terminal is connect with the output end of the crystal oscillator；
The output end of the middle plate of differential capacitor is connected to one end of the signal conditioning circuit；By signal conditioning circuit,
Conditioning processing is carried out to the high-frequency signal of middle plate output modulated；
2nd single-pole double-throw switch (SPDT) has 2A input terminal, 2B input terminal, 2X output end, 2Y output end and 2C
Control terminal；The 2A input terminal is connect with the other end of the signal conditioning circuit；The 2B input terminal and the 4th resistance
(R4) one end connection, the other end ground connection of the 4th resistance (R4)；The 2X output end is connected to one end of the 5th resistance (R5)；
The other end of 5th resistance (R5) draws two branches, and a branch is connect with signal output end；Another branch is connected to the 2nd
One end of capacitor (C2), the other end ground connection of the 2nd capacitor (C2)；2Y output end is empty pin；2C control terminal and crystal shake
Swing the output end connection of device.
2. the modulation-demodulation circuit of force-balanced accelerometer according to claim 1, which is characterized in that the signal
Conditioning circuit includes concatenated operational amplifier and signal filter unit；The output end of the middle plate is connected to the operation
The input terminal of amplifier；The output end of the operational amplifier is connected to the input terminal of the signal filter unit；The signal
The output end of filter unit is connected to the 2A input terminal of the 2nd single-pole double-throw switch (SPDT).
3. the modulation-demodulation circuit of force-balanced accelerometer according to claim 2, which is characterized in that the signal
Filter unit includes the 1st capacitor (C1), the 1st resistance (R1), the 2nd resistance (R2) and the 3rd resistance (R3)；
The input terminal of 1st capacitor (C1) is connect with the output end of the operational amplifier；The output of 1st capacitor (C1)
Two branches are drawn at end, and a branch is connected to one end of the 1st resistance (R1), the other end ground connection of the 1st resistance (R1)；Another
Branch is connected to one end of the 2nd resistance (R2), and the other end of the 2nd resistance (R2) is connected to one end of the 3rd resistance (R3), the 3rd electricity
The other end of resistance (R3) is connected to the 2A input terminal of the 2nd single-pole double-throw switch (SPDT).
4. a kind of modulation /demodulation side of the modulation-demodulation circuit of the described in any item force-balanced accelerometers of claim 1-3
Method, which is characterized in that include the following steps：
Step 1, crystal oscillator exports the alternate signal of low and high level by certain frequency, and simultaneous transmission gives the 1st hilted broadsword respectively
The 1C control terminal of commutator and the 2C control terminal of the 2nd single-pole double-throw switch (SPDT)；
Step 2, for the 1st single-pole double-throw switch (SPDT), when the crystal oscillator exports high level, 1A input terminal and 1X are defeated
Outlet conducting, 1B input terminal be connected with 1Y output end, when crystal oscillator output low level, 1A input terminal and
The conducting of 1Y output end, 1B input terminal are connected with 1X output end；Therefore, when the crystal oscillator is exported by certain frequency
When the alternate signal of low and high level, 1X output end loads same frequency to top crown, amplitude is respectively+12V and -12V height
Frequency square-wave signal；The high-frequency square-wave signal that 1Y output end loads same frequency to bottom crown, amplitude is respectively -12V and+12V,
Being loaded top crown and bottom crown respectively, amplitude is identical, high-frequency square-wave signal of opposite in phase；
Step 3, the middle plate of the differential capacitor acted on by acceleration signal has electrical signal of reaction output, the electrical signal of reaction
Amplitude and phase are directly proportional to the size and Orientation of acceleration signal, and high-frequency square-wave signal exports the middle plate of differential capacitor
Signal has modulating action；The middle plate of differential capacitor exports the high-frequency signal modulated, which passes sequentially through fortune
Calculation amplifier amplifies and after signal filter unit is filtered, the 2A for being transferred to the 2nd single-pole double-throw switch (SPDT) is defeated
Enter end；By signal demodulating circuit synchronous demodulation to low frequency signal, the low frequency signal and acceleration signal are linearly related；
Wherein, signal demodulating circuit synchronous demodulation to low frequency signal process, specially：
When crystal oscillator exports high level, 2A input terminal is connected with 2X output end, and 2B input terminal and 2Y are exported
End conducting；At this point, the 2nd capacitor (C2) is in charged state, i.e.,：High-frequency signal after signal conditioning circuit improves passes through the 2nd
After single-pole double-throw switch (SPDT) and the 5th resistance (R5), charge to the 2nd capacitor (C2)；When crystal oscillator exports low level, 2A is defeated
Enter end to be connected with 2Y output end, 2B input terminal is connected with 2X output end；At this point, the 2nd capacitor (C2) is in discharge condition,
I.e.：2nd capacitor (C2) discharges to the 5th resistance (R5) and the 4th resistance (R4)；Thus make the 2nd capacitor (C2) alternately in charging and
In discharge process, since the conducting resistance of the 2nd single-pole double-throw switch (SPDT) is far smaller than the 4th resistance (R4), the charging time is very short,
Discharge time is very long；Because in the high level period, the 2nd capacitor (C2) quick charge obtains accurate amplitude information；In low electricity
Usually section, the 2nd capacitor (C2) slowly discharge, and keep original amplitude information, to extract modulating wave at the 2nd capacitor (C2) end
Envelope amplitude, i.e. low frequency signal, to realize demodulating process.
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| JPH08178955A (en) * | 1994-12-22 | 1996-07-12 | Murata Mfg Co Ltd | Capacity type electrostatic servo acceleration sensor |
| US5748004A (en) * | 1996-03-15 | 1998-05-05 | Analog Devices, Inc. | Reset switch for a micromachined device |
| CN203519643U (en) * | 2013-11-12 | 2014-04-02 | 中国地震局地球物理研究所 | Differential type force balance acceleration sensor |
| CN106597015A (en) * | 2016-12-02 | 2017-04-26 | 电子科技大学 | Closed-loop circuit for promoting output stability of capacitance type silicon micro-acceleration sensor |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH08178955A (en) * | 1994-12-22 | 1996-07-12 | Murata Mfg Co Ltd | Capacity type electrostatic servo acceleration sensor |
| US5748004A (en) * | 1996-03-15 | 1998-05-05 | Analog Devices, Inc. | Reset switch for a micromachined device |
| CN203519643U (en) * | 2013-11-12 | 2014-04-02 | 中国地震局地球物理研究所 | Differential type force balance acceleration sensor |
| CN106597015A (en) * | 2016-12-02 | 2017-04-26 | 电子科技大学 | Closed-loop circuit for promoting output stability of capacitance type silicon micro-acceleration sensor |
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| 李彩华 等: "智能型力平衡加速度传感器设计", 《国际地震动态》 * |
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